It is going to depend on the size they are looking for which also depends on how far from the set they are sitting. For tube tv's Sony's are great, for all else they aren't very good.
Plasma= Pioneer & Panasonic
DLP= Samsung & Mitsubishi
LCD= Sharp & Panasonic
Hitachi also makes a decent set, but blacks are always w/ green tint.
There are others and Costco does have a great return policy they don't like to advertise.